Heretofore, fuel leaks have developed in the fuel system between an automotive fuel pump and the intake manifold of the engine. This has resulted from malfunctioning fuel inlet valves in the carburetor and vehicle accidents which cause a vehicle to overturn or at impacts which might rupture a fuel line. Further, it is desirable to have a fuel system in which at a vehicle impact of thirty miles per hour no more than one ounce per minute of fuel is leaked from the fuel system. A design to meet this condition is facilitated by a shut-off valve for use with the automotive fuel system with the valve operable to shut off the fuel flow whenever a positive pressure exists in the fuel line from the fuel tank to the shut-off valve.
The leakage of fuel is severe if the vehicle is at rest and the fuel tank is disposed at an elevation higher than the carburetor or engine of the car and this condition frequently exists after overturning of the vehicle or upon impact. The fuel then flows by gravity from the storage tank and if a break in the line or some other leakage occurs, the fuel will flow from the storage tank to create a possible hazard.
The present invention is an improvement over the fuel pump shut-off valve shown in assignee's co-pending application Ser. No. 474,501 to David L. Porter and Raymond E. Williamson, filed May 30, 1974, now U.S. Pat. No. 3,923,425 and entitled, "Fuel Pump Shut-off Valve." Application Ser. No. 474,501 now U.S. Pat. No. 3,923,425 discloses a fuel pump shut-off valve in which the shut-off valve is employed in combination with the fuel pump and is effective to shut off fuel flow whenever a positive pressure exists in the fuel line from the storage tank to the fuel pump.